[PATCH v2 1/2] dmaengine: Add helper dmaengine_prep_submit_slave_single()

[Frank.Li@oss.nxp.com]

From: Frank Li <Frank.Li@nxp.com>

Previously, DMA users had to call dmaengine_prep_slave_single() followed by
dmaengine_submit(). Many DMA consumers missed call dmaengine_desc_free()
when dmaengine_submit() returned an error.

Introduce dmaengine_prep_submit_slave_single() to combine preparation and
submission into a single step and ensure the descriptor is freed on
submission failure.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
change in v2
- use api function dmaengine_prep_submit_slave_single()
---
 drivers/dma/dmaengine.c   | 28 ++++++++++++++++++++++++++++
 include/linux/dmaengine.h | 17 +++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index ca13cd39330ba..1e25be78a22a5 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -1619,6 +1619,34 @@ void dma_run_dependencies(struct dma_async_tx_descriptor *tx)
 }
 EXPORT_SYMBOL_GPL(dma_run_dependencies);
 
+#define dmaengine_prep_submit(chan, cb, cb_param, func, ...)	\
+({	struct dma_async_tx_descriptor *tx =			\
+		dmaengine_prep_##func(chan, __VA_ARGS__);	\
+		dma_cookie_t cookie = -ENOMEM;			\
+								\
+	if (tx) {						\
+		tx->callback = cb;				\
+		tx->callback_param = cb_param;			\
+		cookie = dmaengine_submit(tx);			\
+								\
+		if (dma_submit_error(cookie))			\
+			dmaengine_desc_free(tx);		\
+	}							\
+	cookie;							\
+})
+
+dma_cookie_t
+dmaengine_prep_submit_slave_single(struct dma_chan *chan,
+				   dma_async_tx_callback cb, void *cb_param,
+				   dma_addr_t buf, size_t len,
+				   enum dma_transfer_direction dir,
+				   unsigned long flags)
+{
+	return dmaengine_prep_submit(chan, cb, cb_param, slave_single,
+				     buf, len, dir, flags);
+}
+EXPORT_SYMBOL_GPL(dmaengine_prep_submit_slave_single);
+
 static int __init dma_bus_init(void)
 {
 	int err = dmaengine_init_unmap_pool();
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 99efe2b9b4ea9..0f789fac7e91a 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -990,6 +990,13 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single(
 						  dir, flags, NULL);
 }
 
+dma_cookie_t
+dmaengine_prep_submit_slave_single(struct dma_chan *chan,
+				   dma_async_tx_callback cb, void *cb_param,
+				   dma_addr_t buf, size_t len,
+				   enum dma_transfer_direction dir,
+				   unsigned long flags);
+
 /**
  * dmaengine_prep_peripheral_dma_vec() - Prepare a DMA scatter-gather descriptor
  * @chan: The channel to be used for this descriptor
@@ -1575,6 +1582,16 @@ static inline int dma_get_slave_caps(struct dma_chan *chan,
 {
 	return -ENXIO;
 }
+
+static inline dma_cookie_t
+dmaengine_prep_submit_slave_single(struct dma_chan *chan,
+				   dma_async_tx_callback cb, void *cb_param;
+				   dma_addr_t buf, size_t len,
+				   enum dma_transfer_direction dir,
+				   unsigned long flags);
+{
+	return -ENODEV;
+}
 #endif
 
 static inline int dmaengine_desc_set_reuse(struct dma_async_tx_descriptor *tx)

-- 
2.43.0